Heat-flow sensor

ABSTRACT

A heat-flow sensor that includes an insulating layer, a magnetic field application layer arranged on a first surface of the insulating layer and composed of a conductor, and a heat-flow detection layer arranged on a second surface of the insulating layer, the second surface facing the first surface, and the heat-flow detection layer composed of a conductive magnetic body. The heat-flow detection layer faces the magnetic field application layer via the insulating layer.

TECHNICAL FIELD

The present invention relates to a heat-flow sensor using an anomalousNernst effect.

BACKGROUND ART

A heat-flow sensor is a sensor that measures the amount of heat(hereinafter referred to as heat flow) passing through a unitcross-sectional area per unit time. The heat flow is generated in anon-equilibrium state in which the temperature balance is broken, andincludes information such as a direction and an amount of propagation.Since the heat flow responds faster than the temperature, if the heatflow can be accurately measured, information of the heat can be obtainedearlier than measurement of the temperature.

PTL 1 discloses a heat flux sensor using the Seebeck effect. The heatflux sensor of PTL 1 has a structure in which a first thermoelectricmember made of a P-type semiconductor material and a secondthermoelectric material made of an N-type semiconductor material arealternately connected by a conductor pattern.

PTL 2 discloses a thermoelectric power generation device using theanomalous Nernst effect. The thermoelectric power generation device ofPTL 2 includes a power generator including a plurality of thin wiresmagnetized in the same direction, electrically connected in series, andarranged in parallel to each other. The power generator of PTL 2generates power with a temperature difference in a directionperpendicular to the magnetization direction due to the anomalous Nernsteffect.

CITATION LIST Patent Literature

-   [PTL 1] JP 2019-090756 A-   [PTL 2] JP 6079995 B

SUMMARY OF INVENTION Technical Problem

Since the heat flux sensor of PTL 1 is a Seebeck thermoelectric element,an alternating connection structure (vertical thermopile structure) of aP-type semiconductor and an N-type semiconductor has been required toincrease an extraction voltage. Therefore, the heat flux sensor of PTL 1has the structure in which the first thermoelectric member made of aP-type semiconductor material and the second thermoelectric member madeof an N-type semiconductor material are alternately connected by theconductor pattern and includes many connection points, and thus has aproblem that the structure is complicated and fragile. Further, the heatflux sensor of PTL 1 can have high sensitivity by increasing thethickness in the perpendicular direction but has large thermalresistance in the perpendicular direction by increasing the thickness inthe perpendicular direction, and has a problem that the heat flowflowing in the perpendicular direction is hindered.

Since an electromotive force generated in an in-plane direction by theheat flow flowing in the perpendicular direction can be detected byusing the power generator of PTL 2, a thinner heat-flow sensor than aheat-flow sensor using the Seebeck effect can be implemented. Inaddition, a stably magnetized ferromagnetic metal material has needed tobe applied to the power generator of PTL 2. In the case of a materialwith unstable magnetization, the magnetization state is easily changedby an environmental magnetic field from the outside, and a problem thata sensing function is impaired or becomes unstable arises. Further, toincrease the electromotive force and sensitivity of the heat-flow sensorusing the power generator of PTL 2, it has been necessary to form astructure (horizontal thermopile structure) in which metal materials oftwo types of ferromagnets having different signs and magnitudes of theanomalous Nernst effect are alternately connected.

An object of the present invention is to solve the above-describedproblems and to provide a highly sensitive thin-film heat-flow sensorthat detects heat flow with a single conductive magnetic body.

Solution to Problem

A heat-flow sensor according to one aspect of the present inventionincludes an insulating layer; a magnetic field application layerarranged on a first surface of the insulating layer and including aconductor; and a heat-flow detection layer arranged on a second surfaceof the insulating layer, the second surface facing the first surface,and the heat-flow detection layer including a conductive magnetic body.The heat-flow detection layer faces the magnetic field application layervia the insulating layer.

A heat-flow sensor according to an aspect of the present inventionincludes a substrate; a first magnetic field application layer arrangedon an upper surface of the substrate and including a conductor; a firstinsulating layer arranged on an upper surface of the first magneticfield application layer; a heat-flow detection layer arranged on anupper surface of the first insulating layer and including a conductivemagnetic body; a second insulating layer arranged on an upper surface ofthe heat-flow detection layer; and a second magnetic field applicationlayer arranged on an upper surface of the second insulating layer andincluding a conductor. The heat-flow detection layer faces the firstmagnetic field application layer via the first insulating layer, andfaces the second magnetic field application layer via the secondinsulating layer.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a highlysensitive thin-film heat-flow sensor that detects heat flow with asingle conductive magnetic body.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram illustrating an example of a structure ofa heat-flow sensor according to a first example embodiment.

FIG. 2 is a conceptual diagram for describing a configuration of aheat-flow measurement system according to the first example embodiment.

FIG. 3 is a conceptual diagram illustrating a state in which directcurrents flow through magnetic field application layers of the heat-flowsensor included in the heat-flow measurement system according to thefirst example embodiment.

FIG. 4 is a conceptual diagram illustrating a state in which a heat-flowdetection layer is magnetized when direct currents flow through themagnetic field application layers of the heat-flow sensor included inthe heat-flow measurement system according to the first exampleembodiment.

FIG. 5 is a conceptual diagram illustrating a state in which heat flowflows from an outside in a perpendicular direction to the heat-flowsensor included in the heat-flow measurement system according to thefirst example embodiment.

FIG. 6 is a conceptual diagram illustrating a state in which currentflows in the heat-flow detection layer when heat flow flows from theoutside in the perpendicular direction to the heat-flow sensor includedin the heat-flow measurement system according to the first exampleembodiment.

FIG. 7 is a block diagram illustrating an example of a configuration ofa heat-flow measurement device included in the heat-flow measurementsystem according to the first example embodiment.

FIG. 8 is a flowchart for describing an example of an operation of theheat-flow measurement device included in the heat-flow measurementsystem according to the first example embodiment.

FIG. 9 is a conceptual diagram illustrating an example of a method ofmanufacturing the heat-flow detection layer included in the heat-flowmeasurement system according to the first example embodiment.

FIG. 10 is a conceptual diagram for describing a configuration of aheat-flow measurement system according to a second example embodiment.

FIG. 11 is a block diagram illustrating an example of a configuration ofa heat-flow measurement device included in the heat-flow measurementsystem according to the second example embodiment.

FIG. 12 is a conceptual diagram illustrating a state in which currentflows in a heat-flow detection layer when heat flow flows from anoutside in a perpendicular direction to a heat-flow sensor included inthe heat-flow measurement system according to the second exampleembodiment.

FIG. 13 is a conceptual diagram illustrating a state in which currentflows in the heat-flow detection layer when heat flow flows from theoutside in the perpendicular direction to the heat-flow sensor includedin the heat-flow measurement system according to the second exampleembodiment.

FIG. 14 is a conceptual diagram for describing a voltage detected by aheat-flow detection layer when an alternating current flows through themagnetic field application layer of the heat-flow sensor included in theheat-flow measurement system according to the second example embodiment.

FIG. 15 is a flowchart for describing an example of an operation of theheat-flow measurement device included in the heat-flow measurementsystem according to the second example embodiment.

FIG. 16 is a conceptual diagram illustrating an example of a structureof a heat-flow sensor according to a third example embodiment.

FIG. 17 is a conceptual diagram for describing a configuration of aheat-flow measurement system according to the third example embodiment.

FIG. 18 is a conceptual diagram illustrating a state in which a directcurrent flows through a magnetic field application layer of theheat-flow sensor included in the heat-flow measurement system accordingto the third example embodiment.

FIG. 19 is a conceptual diagram illustrating a state in which aheat-flow detection layer is magnetized when a direct current flowsthrough the magnetic field application layer of the heat-flow sensorincluded in the heat-flow measurement system according to the thirdexample embodiment.

FIG. 20 is a conceptual diagram illustrating a state in which heat flowflows from an outside in a perpendicular direction to the heat-flowsensor included in the heat-flow measurement system according to thethird example embodiment.

FIG. 21 is a conceptual diagram illustrating a state in which currentflows in the heat-flow detection layer when heat flow flows from theoutside in the perpendicular direction to the heat-flow sensor includedin the heat-flow measurement system according to the third exampleembodiment.

FIG. 22 is a conceptual diagram illustrating an example of a structureof a heat-flow sensor according to a configuration example.

FIG. 23 is a block diagram for describing an example of a hardwareconfiguration for implementing a control system according to eachexample embodiment.

EXAMPLE EMBODIMENT

Hereinafter, forms for implementing the present invention will bedescribed with reference to the drawings. The example embodiments to bedescribed below have technically favorable limitations for implementingthe present invention. However, the scope of the invention is notlimited to below. In all the drawings used in the following descriptionof the example embodiments, the same reference numerals are given tosimilar parts unless there is a particular reason. In the followingexample embodiments, repeated description of similar configurations andoperations may be omitted. The directions of the arrows in the drawingsare illustrative and do not limit the directions of signals betweenblocks. In the following example embodiments, an actually measured valueof heat flow is referred to as a heat-flow value.

First Example Embodiment

First, a heat-flow measurement system according to a first exampleembodiment will be described with reference to the drawings. Theheat-flow measurement system of the present example embodiment isprovided with a heat-flow sensor including a heat-flow detection layerincluding a magnetic material exhibiting the anomalous Nernst effect.Hereinafter, the heat-flow sensor will be described, and then theheat-flow measurement system including the heat-flow sensor will bedescribed.

[Heat-Flow Sensor]

FIG. 1 is a conceptual diagram illustrating an example of aconfiguration of a heat-flow sensor 10 included in a heat-flowmeasurement system of the present example embodiment. The heat-flowsensor 10 has a flat plate-like appearance. FIG. 1 is a side view of theflat plate-like heat-flow sensor 10 as viewed from a side.

The heat-flow sensor 10 includes a substrate 11, a first magnetic fieldapplication layer 12, a first insulating layer 13, a heat-flow detectionlayer 14, a second insulating layer 15, a second magnetic fieldapplication layer 16, and a cover layer 17.

The substrate 11 is a base material having an upper surface on which thefirst magnetic field application layer 12 is formed. The substrate 11 ismade of a material that easily conducts heat flow. For example, thesubstrate 11 is made of polyimide. Note that the material of thesubstrate 11 is not limited to polyimide as long as heat flow is easilyconducted.

The first magnetic field application layer 12 is formed on the uppersurface of the substrate 11. The first magnetic field application layer12 is a conductor formed in a predetermined pattern having a first endand a second end. For example, the first magnetic field applicationlayer 12 has a meander shape in which the first end and the second endare arranged at positions separated from each other in top view. Themeander shape is a shape in which ends of adjacent wires are connectedso that a plurality of wires provided in parallel is connected in seriesto form one line as a whole. In the case where the first magnetic fieldapplication layer 12 has the meander shape, a wire having the first endand the second end is arranged so as to be folded back on the surface ofthe substrate 11. The shape of the first magnetic field applicationlayer 12 is not limited to the meander shape as long as the line lengthof the wire from the first end to the second end can be made long.

For example, the first magnetic field application layer 12 is made of ametal material such as copper (Cu), aluminum (Al), or gold (Au). Thematerial of the first magnetic field application layer 12 is not limitedto the metal material such as Cu, Al, or Au as long as the material hasconductivity. For example, the first magnetic field application layer 12can be formed by a sputtering method or a plating method. The firstmagnetic field application layer 12 may be formed by a method other thanthe sputtering method or the plating method.

The first insulating layer 13 is an insulator arranged between the firstmagnetic field application layer 12 and the heat-flow detection layer14. As an example, a surface on which the first magnetic fieldapplication layer 12 is arranged is referred to as a first surface, anda surface on which the heat-flow detection layer 14 is arranged isreferred to as a second surface, of two main surfaces of the firstinsulating layer 13. For example, the first insulating layer 13 is madeof polyimide. The material of the first insulating layer 13 is notlimited to polyimide as long as the material has insulating properties.

The heat-flow detection layer 14 is arranged between the firstinsulating layer 13 and the second insulating layer 15. The heat-flowdetection layer 14 is a conductive magnetic body formed in apredetermined pattern having a first end and a second end. For example,the patterns of the conductors constituting the first magnetic fieldapplication layer 12 and the second magnetic field application layer 16and the pattern of the conductive magnetic body constituting theheat-flow detection layer 14 face each other. For example, the patternsof the conductors constituting the first magnetic field applicationlayer 12 and the second magnetic field application layer 16 and thepattern of the conductive magnetic body included in the heat-flowdetection layer 14 have the same shape. For example, each of the firstmagnetic field application layer 12 and the second magnetic fieldapplication layer 16, and the heat-flow detection layer 14 are arrangedsuch that a line of one pattern extends along the line length of anotherpattern in top view.

The wire pattern of the conductor constituting the heat-flow detectionlayer 14 and the wire patterns of the conductors constituting the firstmagnetic field application layer 12 and the second magnetic fieldapplication layer 16 may not have exactly the same wire width. In a casewhere the wire width of the wire pattern of the conductor constitutingthe heat-flow detection layer 14 is wider, there is a possibility thatthe intensity of magnetization becomes non-uniform and an unevenelectromotive force distribution occurs in the wire of one line ofheat-flow detection layer 14, and the output signal becomes small, ifthere is an influence of misalignment or the like. Therefore, it isdesirable that the wire widths of the wire patterns of the conductorsconstituting the first magnetic field application layer 12 and thesecond magnetic field application layer 16, and the heat-flow detectionlayer 14 are substantially the same, or the wire widths of the firstmagnetic field application layer 12 and the second magnetic fieldapplication layer 16 are wider. In addition, if the wire width of thewire pattern of the conductor constituting heat-flow detection layer 14is too narrow, the internal resistance becomes large and noiseincreases. Therefore, the wire width of the wire pattern of theconductor constituting the heat-flow detection layer 14 is favorablyhalf of or in a similar range of the wire widths of the first magneticfield application layer 12 and the second magnetic field applicationlayer 16.

In addition, the wire pattern of the conductor constituting theheat-flow detection layer 14, and the wire patterns of the conductorsconstituting the first magnetic field application layer 12 and thesecond magnetic field application layer 16 may slightly deviate fromeach other in top view. An allowable deviation is favorably equal to orless than a gap width between the wires of the wire pattern of theconductor constituting heat-flow detection layer 14. In addition, in acase where an insulating layer that fills the gaps between the wires ofthe wire pattern of the conductor constituting the heat-flow detectionlayer 14 is provided, the allowable deviation is favorably equal to orless than the width of the insulating layer. In addition, when alignmentaccuracy of a process of manufacturing the heat-flow detection layer 14,the first magnetic field application layer 12, and the second magneticfield application layer 16 is dx, it is desirable that the gap width(insulating layer width) between the wires of the wire pattern of theconductor constituting the heat-flow detection layer 14 is equal to ormore than dx (dx is a positive real number).

If the distance between the heat-flow detection layer 14 and the firstmagnetic field application layer 12 is equal to the distance between theheat-flow detection layer 14 and the second magnetic field applicationlayer 16, the heat flow generated in the perpendicular direction (zdirection) can be canceled by currents flowing through the firstmagnetic field application layer 12 and the second magnetic fieldapplication layer 16. Therefore, the distance between the heat-flowdetection layer 14 and the first magnetic field application layer 12 isfavorably equal to the distance between the heat-flow detection layer 14and the second magnetic field application layer 16.

For the heat-flow detection layer 14, it is favorable to use a softmagnetic thin film so as to be easily magnetized in the in-planedirection (direction in an xy plane) of the heat-flow sensor 10 by amagnetic field generated by the currents flowing through the firstmagnetic field application layer 12 and the second magnetic fieldapplication layer 16. For example, a soft magnetic material containing ametal such as iron (Fe), aluminum (Al), or nickel (Ni) can be used forthe heat-flow detection layer 14. Specifically, as the material of theheat-flow detection layer 14, an iron-aluminum alloy such as Fe₃Al, apermalloy such as Ni₈₀Fe₂₀, or a metal such as Ni can be used. Forexample, the heat-flow detection layer 14 of Fe₃Al can be formed by asputtering method using a photoresist pattern or a metal mask formed bya photolithography method. Further, for example, the heat-flow detectionlayer 14 of Ni can be formed by a plating method.

The heat-flow detection layer 14 favorably has a shape having a longeffective length in order to enhance the sensing sensitivity. Forexample, the heat-flow detection layer 14 has a meander shape in whichthe first end and the second end are arranged at positions separatedfrom each other in top view, similarly to the first magnetic fieldapplication layer 12. In the case where the heat-flow detection layer 14has a meander shape, the magnetic wire having the first end and thesecond end is arranged so as to be folded back on the surface of thefirst insulating layer 13. In the case where the heat-flow detectionlayer 14 is implemented by a meander-shaped magnetic wire, there is apossibility that the wires interfere with each other to weaken themagnetic field if the distance between adjacent wires is too short.Therefore, it is favorable to arrange the wires with a certain distance.The shape of the heat-flow detection layer 14 is not limited to themeander shape as long as the line length of the wire from the first endto the second end can be made long.

The thinner the heat-flow detection layer 14 is, the more easily theshape-magnetic anisotropy is generated, and thus the heat-flow detectionlayer 14 is easily magnetized in the in-plane direction. However, if theheat-flow detection layer 14 is too thin, the electric resistancebecomes large and noise increases, and thus it is favorable to have thethickness in consideration of the required magnetization and balance. Inaddition, an insulating buffer layer may be provided between a pluralityof wires constituting the heat-flow detection layer 14.

The second insulating layer 15 is an insulator arranged between theheat-flow detection layer 14 and the second magnetic field applicationlayer 16. As an example, a surface on which the second magnetic fieldapplication layer 16 is arranged is referred to as a first surface, anda surface on which the heat-flow detection layer 14 is arranged isreferred to as a second surface, of two main surfaces of the secondinsulating layer 15. The second insulating layer 15 favorably has thesame thickness as the first insulating layer 13. For example, the secondinsulating layer 15 is made of polyimide. The material of the secondinsulating layer 15 is not limited to polyimide as long as the materialhas insulating properties.

The second magnetic field application layer 16 is formed on the uppersurface of the second insulating layer 15. The second magnetic fieldapplication layer 16 is a conductor formed in a predetermined patternhaving a first end and a second end. For example, the second magneticfield application layer 16 is formed in a similar pattern to the firstmagnetic field application layer 12. For example, the second magneticfield application layer 16 and the first magnetic field applicationlayer 12 overlap each other in top view. For example, the secondmagnetic field application layer 16 has a meander shape in which thefirst end and the second end are arranged at positions separated fromeach other in top view. In the case where the second magnetic fieldapplication layer 16 has the meander shape, the wire having the firstend and the second end is arranged so as to be folded back on thesurface of the second insulating layer 15. The shape of the secondmagnetic field application layer 16 is not limited to the meander shapeas long as the line length of the wire from the first end to the secondend can be made long.

For example, the second magnetic field application layer 16 is made of ametal material such as copper, aluminum, or gold. Note that the materialof the second magnetic field application layer 16 is not limited to themetal material such as copper, aluminum, or gold as long as the materialis conductive. For example, the second magnetic field application layer16 can be formed by plating. The second magnetic field application layer16 may be formed by a method other than plating.

The cover layer 17 is formed on the upper surface of the second magneticfield application layer 16. The cover layer 17 is a protective layerthat protects the heat-flow sensor 10. The cover layer 17 is favorablymade of an insulating material having high mechanical strength, chemicalstability, heat resistance, and the like. For example, the cover layer17 is made of polyimide. The material of the cover layer 17 is notlimited to polyimide as long as the material has sufficient mechanicalstrength, chemical stability, heat resistance, and the like.

The range in which the heat-flow sensor 10 detects the heat flow iswithin the range of the pattern of the heat-flow detection layer 14. Inother words, the heat-flow sensor 10 detects the heat flow within therange of the pattern of the heat-flow detection layer 14 to which themagnetic field is applied by the first magnetic field application layer12 and the second magnetic field application layer 16. When theheat-flow sensor 10 is used, the first end of the first magnetic fieldapplication layer 12 and the second end of the second magnetic fieldapplication layer 16, or the second end of the first magnetic fieldapplication layer 12 and the first end of the second magnetic fieldapplication layer 16 are electrically connected by a conductive wire(not illustrated). Then, it is configured such that, when a directcurrent is applied to the first magnetic field application layer 12 andthe second magnetic field application layer 16, the currents flow inopposite directions at facing positions of the first magnetic fieldapplication layer 12 and the second magnetic field application layer 16.

A magnetic field is generated at a position of the heat-flow detectionlayer 14 sandwiched between the first magnetic field application layer12 and the second magnetic field application layer 16 due to the currentflowing through the first magnetic field application layer 12 and thecurrent flowing through the second magnetic field application layer 16.At the position of the heat-flow detection layer 14, the magnetic fieldapplied by the current flowing through the first magnetic fieldapplication layer 12 and the magnetic field applied by the currentflowing through the second magnetic field application layer 16 areadded. The heat-flow detection layer 14 is magnetized in the in-planedirection (in-xy-plane direction) of the heat-flow sensor 10 by themagnetic field applied by the first magnetic field application layer 12and the second magnetic field application layer 16. As the firstmagnetic field application layer 12 and the second magnetic fieldapplication layer 16 are thicker than the heat-flow detection layer 14,the variation in the magnetic field applied to the heat-flow detectionlayer 14 is reduced. Therefore, the first magnetic field applicationlayer 12 and the second magnetic field application layer 16 arefavorably thicker in the film thickness than the heat-flow detectionlayer 14.

The currents flowing through the first magnetic field application layer12 and the second magnetic field application layer 16 are favorablyequal to each other. If the currents flowing through the first magneticfield application layer 12 and the second magnetic field applicationlayer 16 are equal, the heat flows caused by the Joule heat generated bythe currents flowing through the respective magnetic field applicationlayers are canceled. As a result, a thermal gradient in theperpendicular direction perpendicular (in-zy-plane direction) caused bythe Joule heat of the currents flowing through the first magnetic fieldapplication layer 12 and the second magnetic field application layer 16is eliminated, so that the detection sensitivity of the heat flow fromthe outside is improved.

A voltage value V related to an electromotive force generated in theheat-flow detection layer 14 can be expressed by the following equation1, using an electric field E generated in the in-plane direction of theheat-flow detection layer 14 by the anomalous Nernst effect and a linelength L of the wire from a first end 141 to a second end 142 of theheat-flow detection layer 14.

V=EL  (1)

The electric field E based on the anomalous Nernst effect can beexpressed by the following equation 2, using an anomalous Nernstcoefficient Q and magnetic permeability μ of the heat-flow detectionlayer 14, a temperature gradient dT between the upper surface and thelower surface of the heat-flow detection layer 14, and magnetization Mof the heat-flow detection layer 14.

E=Q(μM×dT)  (2)

Further, the temperature gradient dT can be expressed by the followingequation 3, using thermal conductivity λ of the heat-flow detectionlayer 14 and a heat-flow value q passing through the heat-flow detectionlayer 14.

dT=−q/λ,  (3)

By using the above equations 1 to 3, the heat-flow value q related tothe voltage value can be calculated using the voltage value V related tothe electromotive force generated in the heat-flow detection layer 14.

The configuration of the heat-flow sensor 10 included in the heat-flowmeasurement system of the present example embodiment has been described.Note that the configuration of FIG. 1 is an example of the configurationof the heat-flow sensor 10, and the configuration of the heat-flowsensor 10 included in the heat-flow measurement system of the presentexample embodiment is not limited to the configuration of FIG. 1.

[Heat-Flow Measurement System]

Next, the heat-flow measurement system according to the present exampleembodiment will be described with reference to the drawings.

The heat-flow measurement system of the present example embodimentincludes a direct-current power supply for causing the current to flowthrough the first magnetic field application layer 12 and the secondmagnetic field application layer 16 of the heat-flow sensor 10.

FIG. 2 is a conceptual diagram illustrating an example of aconfiguration of the heat-flow measurement system 1 of the presentexample embodiment. As illustrated in FIG. 2, the heat-flow measurementsystem 1 includes the heat-flow sensor 10, a heat-flow measurementdevice 100, a direct-current power supply 110, and a voltmeter 120. InFIG. 2, the first magnetic field application layer 12, the heat-flowdetection layer 14, and the second magnetic field application layer 16,which are stacked in practice, are virtually arranged side by side.

The heat-flow sensor 10 has the structure illustrated in FIG. 1. Theheat-flow sensor 10 includes, as illustrated in FIG. 1, the substrate11, the first magnetic field application layer 12, the first insulatinglayer 13, the heat-flow detection layer 14, the second insulating layer15, the second magnetic field application layer 16, and the cover layer17. In practice, the first magnetic field application layer 12, theheat-flow detection layer 14, and the second magnetic field applicationlayer 16 are stacked In FIG. 2, the cover layer 17 is omitted.

The first magnetic field application layer 12 has a first end 121 and asecond end 122. The heat-flow detection layer 14 has a first end 141 anda second end 142. The second magnetic field application layer 16 has afirst end 161 and a second end 162.

The second end 122 of the first magnetic field application layer 12 iselectrically connected to the second end 162 of the second magneticfield application layer 16. For example, an insulator is filled amongthe second end 162 of the heat-flow detection layer 14, a side surfaceof the heat-flow sensor 10, the first insulating layer 13, and thesecond insulating layer 15. Then, a wire (not illustrated) is arrangedon the side surfaces of the first insulating layer 13 and the secondinsulating layer 15 and the side surface of the heat-flow sensor 10formed of the filled insulator, so that the second end 122 of the firstmagnetic field application layer 12 and the second end 162 of the secondmagnetic field application layer 16 can be electrically connected.Further, for example, by providing a via electrode that penetrates theinsulator filled among the second end 162 of the heat-flow detectionlayer 14, the side surface of the heat-flow sensor 10, the firstinsulating layer 13, and the second insulating layer 15, and the firstinsulating layer 13 and the second insulating layer 15, the second end122 of the first magnetic field application layer 12 and the second end162 of the second magnetic field application layer 16 can beelectrically connected. The via electrode is provided so as not to be incontact with the heat-flow detection layer 14.

The first end 121 of the first magnetic field application layer 12 iselectrically connected to the first end 161 of the second magnetic fieldapplication layer 16 across the direct-current power supply 110. Thefirst end 141 of the heat-flow sensor 10 is electrically connected tothe second end 142 of the heat-flow sensor 10. The voltmeter 120 isarranged between the first end 141 and the second end 142 of theheat-flow sensor 10.

The heat-flow measurement device 100 is connected to direct-currentpower supply 110 and voltmeter 120. The heat-flow measurement device 100drives the direct-current power supply 110 to control the currentflowing through the first magnetic field application layer 12 and thesecond magnetic field application layer 16. In addition, the heat-flowmeasurement device 100 measures the electromotive force generated in theheat-flow detection layer 14 by passage of the heat flow, using thevoltmeter 120.

The direct-current power supply 110 outputs a direct current accordingto the control of the heat-flow measurement device 100. Thedirect-current power supply 110 has a positive electrode connected tothe first end 161 of the second magnetic field application layer 16, anda negative electrode connected to the first end 121 of the firstmagnetic field application layer 12. In the case where the directions ofthe currents flowing through the first magnetic field application layer12 and the second magnetic field application layer 16 are configured tobe opposite, the direct-current power supply 110 has the negativeelectrode connected to the first end 161 of the second magnetic fieldapplication layer 16, and the positive electrode connected to the firstend 121 of the first magnetic field application layer 12.

The voltmeter 120 is a direct-current voltmeter connected to the firstend 141 and the second end 142 of the heat-flow detection layer 14. Thevoltmeter 120 measures the voltage between the first end 141 and thesecond end 142 of the heat-flow detection layer 14, and outputs ameasured voltage value to the heat-flow measurement device 100.

FIG. 3 is a conceptual diagram illustrating a state in which thecurrents flow through the first magnetic field application layer 12 andthe second magnetic field application layer 16 by arrows. As illustratedin FIG. 3, the currents flow through the first magnetic fieldapplication layer 12 and the second magnetic field application layer 16in directions opposite to each other. FIG. 3 illustrates an example inwhich the heat-flow measurement device 100 drives the direct-currentpower supply 110 to cause the current to flow from the first end 161 tothe second end 162 of the second magnetic field application layer 16 andfrom the second end 122 to the first end 121 of the first magnetic fieldapplication layer 12.

FIG. 4 is a conceptual diagram illustrating a state in which theheat-flow detection layer 14 is magnetized by the magnetic fieldsgenerated in the first magnetic field application layer 12 and thesecond magnetic field application layer 16 when the currents flowthrough the first magnetic field application layer 12 and the secondmagnetic field application layer 16 as illustrated in FIG. 3. Asillustrated in FIG. 4, when the currents flow through the first magneticfield application layer 12 and the second magnetic field applicationlayer 16, the magnetic fields are generated around the wiresconstituting the first magnetic field application layer 12 and thesecond magnetic field application layer 16 according to the Ampere'slaw. The magnetic fields around the wires constituting the firstmagnetic field application layer 12 and the second magnetic fieldapplication layer 16 are added at the position of the wire constitutingthe heat-flow detection layer 14 and magnetize the heat-flow detectionlayer 14. As illustrated in FIG. 4, among the wires constituting theheat-flow detection layer 14, adjacent wires are magnetized in thedirections opposite to each other.

In addition, the heat flow due to Joule heat is also generated from theinside of the heat-flow sensor 10 when the currents flow through thefirst magnetic field application layer 12 and the second magnetic fieldapplication layer 16. The heat-flow sensor 10 has a verticallysymmetrical structure having the heat-flow detection layer 14 sandwichedbetween the first magnetic field application layer 12 and the secondmagnetic field application layer 16, and the first magnetic fieldapplication layer 12 and the second magnetic field application layer 16are connected in series. Therefore, equal currents flow through thefirst magnetic field application layer 12 and the second magnetic fieldapplication layer 16. As a result, since the heat flow generated in thefirst magnetic field application layer 12 and the heat flow generated inthe second magnetic field application layer 16 cancel each other in theheat-flow detection layer 14, the electromotive force is not generatedin the heat-flow detection layer 14 in a state where there is no heatflow from the outside.

FIG. 5 is a conceptual diagram illustrating a situation in which theheat flow has arrived from the outside in the state where the currentsflow through the first magnetic field application layer 12 and thesecond magnetic field application layer 16 as illustrated in FIGS. 3 and4. FIG. 6 is a conceptual diagram illustrating a state in which theelectromotive force is generated in the heat-flow detection layer 14 andthe current flows in the heat-flow detection layer 14 in the situationin which the heat flow has arrived from the outside in the state wherethe currents flow through the first magnetic field application layer 12and the second magnetic field application layer 16.

When the heat flow passes through the heat-flow detection layer 14 fromthe first magnetic field application layer 12 toward the second magneticfield application layer 16 as illustrated in FIG. 5, the electromotiveforce due to the anomalous Nernst effect is generated in each conductivemagnetic body constituting the heat-flow detection layer 14. As a resultof the electromotive force generated at this time being added in theheat-flow detection layer 14 having the meander shape structure, anoutput voltage can be detected between the first end 141 and the secondend 142 of the heat-flow detection layer 14. Since the output voltagebetween the first end 141 and the second end 142 of the heat-flowdetection layer 14 is proportional to the heat-flow value, the heat flowpassing through the heat-flow detection layer 14 can be measured byconverting the detected output voltage into the heat-flow value.

The configuration of the heat-flow measurement system 1 of the presentexample embodiment has been described. The configuration of FIGS. 2 to 5is an example of the configuration of the heat-flow measurement system1, and the configuration of the heat-flow measurement system 1 of thepresent example embodiment is not limited to the configuration of FIGS.2 to 5.

[Heat-Flow Measurement Device]

Next, the heat-flow measurement device 100 included in the heat-flowmeasurement system 1 of the present example embodiment will be describedwith reference to the drawings. FIG. 7 is a block diagram illustratingan example of a configuration of the heat-flow measurement device 100.As illustrated in FIG. 7, the heat-flow measurement device 100 includesa power supply control unit 101, a voltage measurement unit 102, aheat-flow calculation unit 103, and an output unit 107. FIG. 7illustrates an example in which an output device 130 for outputting theheat-flow value measured by the heat-flow measurement device 100 isconnected to the output unit 107.

The power supply control unit 101 is connected to the direct-currentpower supply 110. The power supply control unit 101 drives thedirect-current power supply 110 to control the current flowing throughthe first magnetic field application layer 12 and the second magneticfield application layer 16. The current value of the current flowingthrough the first magnetic field application layer 12 and the secondmagnetic field application layer 16 by the power supply control unit 101is a preset value. Note that the current value of the current flowingthrough the first magnetic field application layer 12 and the secondmagnetic field application layer 16 may be set to be changeable by thepower supply control unit 101.

The voltage measurement unit 102 is connected to the voltmeter 120.Further, the voltage measurement unit 102 is connected to the heat-flowcalculation unit 103. The voltage measurement unit 102 acquires thevoltage value of the electromotive force generated in the heat-flowdetection layer 14 from the voltmeter 120. The voltage measurement unit102 outputs the acquired voltage value of the electromotive force of theheat-flow detection layer 14 to the heat-flow calculation unit 103.

The heat-flow calculation unit 103 is connected to the voltagemeasurement unit 102. The heat-flow calculation unit 103 is connected tothe output unit 107. The heat-flow calculation unit 103 acquires thevoltage value related to the electromotive force generated in theheat-flow detection layer 14 from the voltage measurement unit 102. Theheat-flow calculation unit 103 converts the acquired voltage value intothe heat-flow value. The heat-flow calculation unit 103 outputs thecalculated heat-flow value to the output unit 107.

The output unit 107 acquires the heat-flow value from the heat-flowcalculation unit 103. The output unit 107 outputs the acquired heat-flowvalue to the output device 130.

The output device 130 acquires the heat-flow value from the output unit107. The output device 130 outputs the acquired heat-flow value. Forexample, the output device 130 is implemented by a display device havinga monitor that displays information regarding the heat-flow value.Further, for example, the output device 130 is implemented by a printerthat prints the information regarding the heat-flow value on a mediumsuch as paper. Further, for example, the output device 130 isimplemented by a speaker that notifies the information regarding theheat-flow value by sound. The output device 130 is not particularlylimited as long as the output device can output the informationregarding the heat-flow value.

The heat-flow measurement device 100 included in the heat-flowmeasurement system 1 of the present example embodiment has beendescribed above. Note that the heat-flow measurement device 100 of FIG.7 is an example, and the heat-flow measurement device 100 included inthe heat-flow measurement system 1 of the present example embodiment isnot limited to the form of FIG. 7.

(Operation)

Next, an operation of the heat-flow measurement device 100 included inthe heat-flow measurement system 1 of the present example embodimentwill be described with reference to the drawings. FIG. 8 is a flowchartfor describing an example of the operation of the heat-flow measurementdevice 100. In the description of the operation of the heat-flowmeasurement device 100 along the flowchart of FIG. 8, the componentsconstituting the heat-flow measurement device 100 are the mainconstituents, but the heat-flow measurement device 100 can also beregarded as a main constituent.

In FIG. 8, first, the power supply control unit 101 of the heat-flowmeasurement device 100 drives the direct-current power supply 110 tocause the current to flow through the first magnetic field applicationlayer 12 and the second magnetic field application layer 16 (step S11).

Next, the voltage measurement unit 102 of the heat-flow measurementdevice 100 measures the voltage value measured by the voltmeter 120(step S12).

Here, in a case where the voltage value measured by the voltagemeasurement unit 102 of the heat-flow measurement device 100 does notexceed a threshold value (No in step S13), the processing returns tostep S12.

On the other hand, in a case where the voltage value measured by thevoltage measurement unit 102 of the heat-flow measurement device 100exceeds the threshold value (Yes in step S13), the heat-flow calculationunit 103 of the heat-flow measurement device 100 calculates theheat-flow value using the voltage value (step S14).

Then, the output unit 107 of the heat-flow measurement device 100outputs the calculated heat-flow value to the output device 130 (stepS15).

Here, in a case where the measurement of the heat flow is continued (Yesin step S16), the processing returns to step S12. On the other hand, ina case where the measurement of the heat flow is terminated (No in stepS16), the processing according to the flowchart of FIG. 8 is terminated.

The operation of the heat-flow measurement device 100 included in theheat-flow measurement system 1 of the present example embodiment hasbeen described above. The operation of the heat-flow measurement device100 of FIG. 8 is an example, and the operation of the heat-flowmeasurement device 100 included in the heat-flow measurement system 1 ofthe present example embodiment is not limited to the procedure of FIG.8.

[Manufacturing Method]

Next, a method of manufacturing the heat-flow detection layer 14included in the heat-flow sensor 10 of the heat-flow measurement system1 of the present example embodiment will be described with reference tothe drawings. FIG. 9 is a conceptual diagram for describing an exampleof the method of manufacturing the heat-flow detection layer 14. FIG. 9illustrates an example in which the heat-flow detection layer 14 isformed by plating.

FIG. 9(a) illustrates a plate in which an insulating layer 151 forforming a pattern of the heat-flow detection layer 14 is formed on asurface of a conductive base material 152.

FIG. 9(b) illustrates a state in which a plating layer 153 having thepattern of the heat-flow detection layer 14 is plated on the surface ofthe conductive base material 152. The plating layer 153 is formed on thesurface of the conductive base material 152 that is not covered with theinsulating layer 151. For example, the plating layer 153 is a softmagnetic material such as an iron-aluminum alloy or a permalloy.

FIG. 9(c) illustrates a state in which the plating layer 153 formed onthe surface of conductive base material 152 is transferred to a transferfilm 154. For example, the transfer film 154 is an insulating materialsuch as polyimide. The transfer film 154 corresponds to the firstinsulating layer 13.

FIG. 9(d) illustrates a state in which the transfer film 154 (firstinsulating layer 13) is peeled off from the plate on which theinsulating layer 151 for forming the pattern of the heat-flow detectionlayer 14 is formed on the surface of the conductive base material 152.As illustrated in FIG. 9(d), the plating layer 153 (heat-flow detectionlayer 14) is formed on one surface of the transfer film 154 (firstinsulating layer 13).

The above is description about the method of manufacturing the heat-flowdetection layer 14 included in the heat-flow sensor 10 of the heat-flowmeasurement system 1 of the present example embodiment. Note that themethod of manufacturing the heat-flow detection layer 14 in

FIG. 9 is an example, and the method of manufacturing the heat-flowdetection layer 14 of the present example embodiment is not limited tothe procedure illustrated in FIG. 9.

As described above, the heat-flow sensor of the present exampleembodiment includes the substrate, the first magnetic field applicationlayer, the first insulating layer, the heat-flow detection layer, thesecond insulating layer, and the second magnetic field applicationlayer. The first magnetic field application layer is arranged on theupper surface of the substrate and is made of a conductor. The firstinsulating layer is arranged on the upper surface of the first magneticfield application layer. The heat-flow detection layer is arranged onthe upper surface of the first insulating layer and is made of aconductive magnetic body. The second insulating layer is arranged on theupper surface of the heat-flow detection layer. The second magneticfield application layer is arranged on the upper surface of the secondinsulating layer and is made of a conductor. The heat-flow detectionlayer faces the first magnetic field application layer via the firstinsulating layer, and faces the second magnetic field application layervia the second insulating layer.

In one aspect of the present example embodiment, the patterns of theconductors constituting the first magnetic field application layer andthe second magnetic field application layer, and the pattern of theconductive magnetic body constituting the heat-flow detection layer faceeach other. Further, in one aspect of the present example embodiment,each of the first magnetic field application layer and the secondmagnetic field application layer, and the heat-flow detection layer areprovided via each of the first insulating layer and the secondinsulating layer, and the wire pattern of the heat-flow detection layeris provided facing the wire pattern of each of the first magnetic fieldapplication layer and the second magnetic field application layer.Further, in one aspect of the present example embodiment, the patternsof the conductors constituting the first magnetic field applicationlayer and the second magnetic field application layer, and the patternof the conductive magnetic body constituting the heat-flow detectionlayer have the same shape. Further, in one aspect of the present exampleembodiment, the line of the pattern of the conductive magnetic bodyconstituting the heat-flow detection layer is arranged to extend alongthe line length of the pattern of the conductor constituting each of thefirst magnetic field application layer and the second magnetic fieldapplication layer in top view.

In one aspect of the present example embodiment, the heat-flow detectionlayer is made of a soft magnetic conductive magnetic body. In one aspectof the present example embodiment, the distance between the firstmagnetic field application layer and the heat-flow detection layer isequal to the distance between the second magnetic field applicationlayer and the heat-flow detection layer. In one aspect of the presentexample embodiment, the first magnetic field application layer, thesecond magnetic field application layer, and the heat-flow detectionlayer are configured in the pattern having the shape in which one wireis folded back. In one aspect of the present example embodiment, thefirst magnetic field application layer, the second magnetic fieldapplication layer, and the heat-flow detection layer are configured inthe meander pattern. In one aspect of the present example embodiment,the first magnetic field application layer and the second magnetic fieldapplication layer are thicker in the film thickness than the heat-flowdetection layer.

In addition, the heat-flow measurement system of the present exampleembodiment includes the heat-flow sensor and the heat-flow measurementdevice described above. The heat-flow measurement device controls thecurrent flowing through the first magnetic field application layer andthe second magnetic field application layer, measures the voltage of theheat-flow detection layer, and converts the measured voltage value intoa heat-flow value.

In the heat-flow measurement system according to one aspect of thepresent example embodiment, each of the first magnetic field applicationlayer, the second magnetic field application layer, and the heat-flowdetection layer has the first end and the second end. The first ends ofthe first magnetic field application layer and the second magnetic fieldapplication layer are electrically connected to each other. The secondends of the first magnetic field application layer and the secondmagnetic field application layer are connected via the direct-currentpower supply. The heat-flow measurement device performs control to causethe direct current to flow from the second end of either the firstmagnetic field application layer or the second magnetic fieldapplication layer, and measures the voltage between the first end andthe second end of the heat-flow detection layer.

According to the present example embodiment, by configuring theheat-flow detection layer made of a conductive magnetic body to besandwiched by the two magnetic field application layers, the magneticfield can be effectively applied in the in-plane direction of theheat-flow detection layer. In addition, according to the present exampleembodiment, since the current values of the currents flowing through thetwo magnetic field application layers are equal, it is possible tooffset the heat flow caused by the Joule heat generated by the currentsflowing through the two magnetic field application layers.

In addition, according to the present example embodiment, a locallydifferent non-uniform magnetic field, not a uniform magnetic field fromthe outside, can be applied to the heat-flow detection layer made of themeander-shaped conductive magnetic body made of a single material. Thatis, according to the present example embodiment, since a stable magneticfield can be intensively applied to the portion of the meander-shapedconductive magnetic body constituting the heat-flow detection layer, ahighly sensitive heat-flow sensor can be obtained.

That is, according to the heat-flow sensor of the present exampleembodiment, by non-uniformly magnetizing the heat-flow detection layerusing the magnetic field application layers that generate non-uniformmagnetic fields, it is possible to configure the thermoelectric layerhaving a high extraction voltage with a single material. In other words,according to the present example embodiment, it is possible to provide ahighly sensitive thin-film heat-flow sensor that detects heat flow witha single conductive magnetic body.

Second Example Embodiment

Next, a heat-flow measurement system according to a second exampleembodiment will be described with reference to the drawings. Theheat-flow measurement system of the present example embodiment isdifferent from the heat-flow measurement system of the first exampleembodiment in including an alternating-current power supply instead of adirect-current power supply.

FIG. 10 is a conceptual diagram illustrating an example of aconfiguration of a heat-flow measurement system 2 of the present exampleembodiment. As illustrated in FIG. 10, the heat-flow measurement system1 includes a heat-flow sensor 20, a heat-flow measurement device 200, analternating-current power supply 210, and a voltmeter 220. In FIG. 10, afirst magnetic field application layer 22, a heat-flow detection layer24, and a second magnetic field application layer 26, which are stackedin practice, are arranged side by side. The alternating-current powersupply 210 outputs an alternating current with polarity switched inaccordance with a set period.

The heat-flow sensor 20 has a similar structure to the heat-flow sensor10 illustrated in FIG. 1. The heat-flow sensor 20 has a structure inwhich the first magnetic field application layer 22, a first insulatinglayer 23, the heat-flow detection layer 24, a second insulating layer25, the second magnetic field application layer 26, and a cover layer(not illustrated) are sequentially stacked on an upper surface of asubstrate 21. In practice, the first magnetic field application layer22, the heat-flow detection layer 24, and the second magnetic fieldapplication layer 26 are stacked. In FIG. 10, the cover layer isomitted. Hereinafter, description of configurations similar to those ofthe heat-flow sensor 10 may be omitted. As an example, a surface onwhich the first magnetic field application layer 22 is arranged isreferred to as a first surface, and a surface on which the heat-flowdetection layer 24 is arranged is referred to as a second surface, oftwo main surfaces of the first insulating layer 23. Further, as anexample, a surface on which the second magnetic field application layer26 is arranged is referred to as a first surface, and a surface on whichthe heat-flow detection layer 24 is arranged is referred to as a secondsurface, of two main surfaces of the second insulating layer 25.

The first magnetic field application layer 22 has a first end 221 and asecond end 222. The heat-flow detection layer 24 has a first end 241 anda second end 242. The second magnetic field application layer 26 has afirst end 261 and a second end 262. For example, the first magneticfield application layer 22, the heat-flow detection layer 24, and thesecond magnetic field application layer 26 have a meander shape andoverlap one another in top view.

The second end 222 of the first magnetic field application layer 22 iselectrically connected to the second end 262 of the second magneticfield application layer 26. For example, in a state where the layers arestacked as illustrated in FIG. 1, the second end 222 of the firstmagnetic field application layer 22 and the second end 262 of the secondmagnetic field application layer 26 are electrically connected by wire(not illustrated) arranged along a side surface of the heat-flow sensor20. The first end 221 of the first magnetic field application layer 22is electrically connected to the first end 261 of the second magneticfield application layer 26 across the alternating-current power supply210. The first end 241 of the heat-flow sensor 20 is electricallyconnected to the second end 242 of the heat-flow sensor 20. Thevoltmeter 220 is arranged between the first end 241 and the second end242 of the heat-flow sensor 20.

The heat-flow measurement device 200 is connected to thealternating-current power supply 210 and the voltmeter 220. Theheat-flow measurement device 200 drives the alternating-current powersupply 210 to control the alternating current flowing through the firstmagnetic field application layer 22 and the second magnetic fieldapplication layer 26. In addition, the heat-flow measurement device 200measures an electromotive force generated in the heat-flow detectionlayer 24 by passage of the heat flow, using the voltmeter 220.

The alternating-current power supply 210 outputs an alternating currentaccording to the control of the heat-flow measurement device 200. Thealternating-current power supply 210 is connected between the first end261 of the second magnetic field application layer 26 and the first end221 of the first magnetic field application layer 22.

The voltmeter 220 is an alternating-current voltmeter connected to thefirst end 241 and the second end 242 of the heat-flow detection layer24. The voltmeter 220 measures the voltage between the first end 241 andthe second end 242 of the heat-flow detection layer 24, and outputs ameasured voltage value to the heat-flow measurement device 200.

The configuration of the heat-flow measurement system 2 of the presentexample embodiment has been described. Note that the configuration ofFIG. 10 is an example of the configuration of the heat-flow measurementsystem 2, and the configuration of the heat-flow measurement system 2 ofthe present example embodiment is not limited to the configuration ofFIG. 10.

[Heat-Flow Measurement Device]

Next, the heat-flow measurement device 200 included in the heat-flowmeasurement system 2 of the present example embodiment will be describedwith reference to the drawings. FIG. 11 is a block diagram illustratingan example of a configuration of the heat-flow measurement device 200.As illustrated in FIG. 11, the heat-flow measurement device 200 includesa power supply control unit 201, a voltage measurement unit 202, aheat-flow calculation unit 203, a correction unit 205, and an outputunit 207. FIG. 11 illustrates an example in which an output device 230for outputting the amount of heat measured by the heat-flow measurementdevice 200 is connected to the output unit 207.

The power supply control unit 201 is connected to thealternating-current power supply 210. The power supply control unit 201drives the alternating-current power supply 210 to control thealternating current flowing through the first magnetic field applicationlayer 12 and the second magnetic field application layer 16. The currentvalue of the current flowing through the first magnetic fieldapplication layer 22 and the second magnetic field application layer 26by the power supply control unit 201 is a preset value. Note that aneffective value of the alternating current flowing through the firstmagnetic field application layer 22 and the second magnetic fieldapplication layer 26 may be set to be changeable by the power supplycontrol unit 201.

The voltage measurement unit 202 is connected to the voltmeter 220. Inaddition, the voltage measurement unit 202 is connected to the heat-flowcalculation unit 203. The voltage measurement unit 202 acquires thevoltage value of the electromotive force generated in the heat-flowdetection layer 24 from the voltmeter 220. The voltage measurement unit202 outputs the acquired voltage value of the electromotive force of theheat-flow detection layer 24 to the heat-flow calculation unit 203.

Here, the voltage measured by the voltage measurement unit 202 will bedescribed with reference to the drawings. FIGS. 12 and 13 are conceptualdiagrams for describing that the direction of the current flowingthrough the heat-flow detection layer 24 changes depending on thedirection of the currents flowing through the first magnetic fieldapplication layer 22 and the second magnetic field application layer 26constituting the heat-flow sensor 20. In the examples of FIGS. 12 and13, it is assumed that heat flow flows from the first magnetic fieldapplication layer 22 toward the second magnetic field application layer26 in a perpendicular direction (+z direction) with respect to theheat-flow sensor 20.

FIG. 12 is a conceptual diagram illustrating a situation in which thecurrent flows out from the alternating-current power supply 210 in a −xdirection. In the example of FIG. 12, the current flowing in a +ydirection from the first end 261 of the second magnetic fieldapplication layer 26 repeatedly changes the direction along the ydirection and flows out from the second end 262. The current flowing outfrom the second end 262 of the second magnetic field application layer26 flows in the −y direction from the second end 222 of the firstmagnetic field application layer 22. The current flowing in the −ydirection from the second end 222 of the first magnetic fieldapplication layer 22 repeatedly changes the direction along the ydirection and flows out from the first end 221.

In the example of FIG. 12, in the situation where the heat flow flows inthe perpendicular direction (+z direction) from the first magnetic fieldapplication layer 22 toward the second magnetic field application layer26, the current flows from the first end 241 toward the second end 242of the heat-flow detection layer 24.

FIG. 13 is a conceptual diagram illustrating a situation in which thecurrent flows out from the alternating-current power supply 210 in the+x direction. In the example of FIG. 13, the current flowing in the +ydirection from the first end 221 of the first magnetic field applicationlayer 22 repeatedly changes the direction along the y direction andflows out from the second end 222. The current flowing out from thesecond end 222 of the first magnetic field application layer 22 flows inthe −y direction from the second end 262 of the second magnetic fieldapplication layer 26. The current flowing in the −y direction from thesecond end 262 of the second magnetic field application layer 26repeatedly changes the direction along the y direction and flows outfrom the first end 261.

In the example of FIG. 13, in the situation where the heat flow flows inperpendicular direction (+z direction) from the first magnetic fieldapplication layer 22 toward the second magnetic field application layer26, the current flows from the second end 242 toward the first end 241of the heat-flow detection layer 24.

The heat-flow calculation unit 203 is connected to the voltagemeasurement unit 202. In addition, the heat-flow calculation unit 203 isconnected to the correction unit 205. The heat-flow calculation unit 203acquires the voltage value related to the electromotive force generatedin the heat-flow detection layer 24 from the voltage measurement unit202. The heat-flow calculation unit 203 converts the acquired voltagevalue into a heat-flow value. The heat-flow calculation unit 203 outputsthe calculated heat-flow value to the correction unit 205. The polarityof the heat-flow value calculated by the heat-flow calculation unit 203is periodically changed according to the direction in which the currentflows.

The correction unit 205 acquires the heat-flow value calculated by theheat-flow calculation unit 203. The correction unit 205 corrects theacquired heat-flow value. As an example, the correction unit 205 sets anaverage value of a maximum value and a minimum value of the heat-flowvalue as a baseline, and corrects the heat-flow value in accordance withthe baseline. The correction unit 205 outputs the corrected heat-flowvalue to the output unit 207.

FIG. 14 is a conceptual diagram illustrating a temporal change of thevoltage value with the polarity changing according to the currentflowing from the alternating-current power supply 210 in the situationwhere the heat flow flows in the substantially perpendicular direction(+z direction) from the first magnetic field application layer 22 towardthe second magnetic field application layer 26.

For example, a case where a heat flow component in an in-plane direction(xy plane) is present in addition to a heat flow component in theperpendicular direction (z direction), or a case where a heat flowdistribution in an element surface is non-uniform due to a large heatflow distribution is assumed. In such a case, when the heat flow flowsin the substantially perpendicular direction (+z direction) from thefirst magnetic field application layer 22 toward the second magneticfield application layer 26, an offset voltage of an electromotive forcecaused by the Seebeck effect may be applied to the heat-flow detectionlayer 14 in addition to an electromotive force caused by the anomalousNernst effect. Since the electromotive force caused by the anomalousNernst effect is generated perpendicular to a heat flow direction, theelectromotive force (voltage value V) in the in-plane directiongenerated between the first end and the second end of the heat-flowdetection layer 14 is proportional to the heat flow in the perpendiculardirection (z direction). In contrast, since the electromotive forcecaused by the Seebeck effect is generated along the heat flow direction,the electromotive force (voltage value V) in the in-plane directiongenerated between the first end and the second end depends on the heatflow in the in-plane direction (in xy-plane direction). Therefore, avoltage value V1 detected when the current flows out from thealternating-current power supply 210 in the +x direction and a voltagevalue V2 detected when the current flows out from thealternating-current power supply 210 in the −x direction are shifted bythe contribution of the Seebeck effect.

In the present example embodiment, the direction of an electromotiveforce Va in the perpendicular direction (z direction) caused by theanomalous Nernst effect changes according to the change in the polarityof the alternating current from the alternating-current power supply210. In contrast, the direction of an electromotive force Vs in theperpendicular direction (z direction) caused by the Seebeck effect doesnot change according to the change in the polarity of the alternatingcurrent from the alternating-current power supply 210. Therefore, bycalculating an average value of the voltage value V1 and the voltagevalue V2 using the following equation 4, the electromotive force Vscaused by the Seebeck effect is removed, and the electromotive force Vacaused by the anomalous Nernst effect can be calculated.

|Va|=(V1+V2)/2  (4)

The output unit 207 acquires the heat-flow value from the correctionunit 205. The output unit 207 outputs the acquired heat-flow value tothe output device 230.

The output device 230 acquires the heat-flow value from the output unit207. The output device 230 outputs the acquired heat-flow value. Forexample, the output device 230 is implemented by a display device havinga monitor that displays information regarding the heat-flow value.Further, for example, the output device 230 is implemented by a printerthat prints the information regarding the heat-flow value on a mediumsuch as paper. Further, for example, the output device 230 isimplemented by a speaker that notifies the information regarding theheat-flow value by sound. The output device 230 is not particularlylimited as long as the output device can output the informationregarding the heat-flow value.

The heat-flow measurement device 200 included in the heat-flowmeasurement system 2 of the present example embodiment has beendescribed above. Note that the heat-flow measurement device 200 of FIG.11 is an example, and the heat-flow measurement device 200 included inthe heat-flow measurement system 2 of the present example embodiment isnot limited to the form of FIG. 11.

(Operation)

Next, an operation of the heat-flow measurement device 200 included inthe heat-flow measurement system 2 of the present example embodimentwill be described with reference to the drawings. FIG. 15 is a flowchartfor describing an example of the operation of the heat-flow measurementdevice 200. In the description of the operation of the heat-flowmeasurement device 200 along the flowchart of FIG. 15, the componentsconstituting the heat-flow measurement device 200 are the mainconstituents, but the heat-flow measurement device 200 can also beregarded as a main constituent.

In FIG. 15, first, the power supply control unit 201 of the heat-flowmeasurement device 200 drives the alternating-current power supply 210to cause the current to flow through the first magnetic fieldapplication layer 22 and the second magnetic field application layer 26(step S21).

Next, the voltage measurement unit 202 of the heat-flow measurementdevice 200 measures the voltage value measured by the voltmeter 220(step S22).

Here, in a case where the voltage value measured by the voltagemeasurement unit 202 of the heat-flow measurement device 200 does notexceed a threshold value (No in step S23), the processing returns tostep S22.

On the other hand, in a case where the voltage value measured by thevoltage measurement unit 202 of the heat-flow measurement device 200exceeds the threshold value (Yes in step S23), the heat-flow calculationunit 203 of the heat-flow measurement device 200 calculates theheat-flow value using the voltage value (step S24).

Next, the correction unit 205 of the heat-flow measurement device 200corrects the heat-flow value calculated by the heat-flow calculationunit 203 (step S25).

Then, the output unit 207 of the heat-flow measurement device 200outputs the calculated heat-flow value to the output device 230 (stepS26).

Here, in a case where the measurement of the heat flow is continued (Yesin step S27), the processing returns to step S22. On the other hand, ina case where the measurement of the heat flow is terminated (No in stepS27), the processing according to the flowchart of FIG. 15 isterminated.

The operation of the heat-flow measurement device 200 included in theheat-flow measurement system 2 of the present example embodiment hasbeen described above. The operation of the heat-flow measurement device200 of FIG. 15 is an example, and the operation of the heat-flowmeasurement device 200 included in the heat-flow measurement system 2 ofthe present example embodiment is not limited to the procedure of FIG.15.

As described above, the heat-flow measurement system of the presentexample embodiment includes the heat-flow sensor and the heat-flowmeasurement device described above. The heat-flow measurement devicecontrols the current to flow through the first magnetic fieldapplication layer and the second magnetic field application layer,measures the voltage of the heat-flow detection layer, and converts themeasured voltage value into the heat-flow value.

In the heat-flow measurement system according to one aspect of thepresent example embodiment, each of the first magnetic field applicationlayer, the second magnetic field application layer, and the heat-flowdetection layer has the first end and the second end. The first ends ofthe first magnetic field application layer and the second magnetic fieldapplication layer are electrically connected to each other. The secondends of the first magnetic field application layer and the secondmagnetic field application layer are connected via thealternating-current power supply. The heat-flow measurement deviceperforms control to cause the alternating current to flow from thesecond end of each of the first magnetic field application layer and thesecond magnetic field application layer, and measures the voltagebetween the first end and the second end of the heat-flow detectionlayer.

In one aspect of the present example embodiment, the heat-flowmeasurement device sets the average value of the maximum value and theminimum value of the voltage between the first end and the second end ofthe heat-flow detection layer as the baseline and corrects the heat-flowvalue.

According to the present example embodiment, a locally differentnon-uniform magnetic field in which the direction is periodicallychanged can be applied to the heat-flow detection layer made of themeander-shaped conductive magnetic body made of a single material.According to the present example embodiment, since the electromotiveforce caused by the Seebeck effect generated in the in-plane directioncan be removed by the heat flow flowing in the perpendicular directionof the heat-flow sensor, using the fact that magnetization of theheat-flow sensor is periodically reversed by the alternating current, ahighly accurate heat-flow sensor can be obtained.

Further, according to the present example embodiment, the offset signalthat can be caused by the Seebeck effect, noise, or the like can bedetermined, and the offset signal can be removed. Moreover, according tothe present example embodiment, more highly sensitive heat flow sensingcan be implemented by lock-in detection or the like.

For example, in a case where the heat flow to be measured is small, thevoltage signal caused by the heat flow may be buried in noise of variousfrequencies. According to the method of the present example embodiment,since it is known that the signal caused by the heat flow is modulatedat the same frequency as the alternating current, noise of otherfrequency components can be removed by cutting off only the frequencycomponent with a filter. As a result, according to the method of thepresent example embodiment, the voltage signal caused by the heat flowburied in the noise of various frequencies can be extracted with highsensitivity.

Third Example Embodiment

Next, a heat-flow measurement system according to a third exampleembodiment will be described with reference to the drawings. Theheat-flow measurement system of the present example embodiment isdifferent from the heat-flow measurement system of the first exampleembodiment in that a magnetic field application layer is formed of onelayer. Hereinafter, the heat-flow sensor will be described, and then theheat-flow measurement system including the heat-flow sensor will bedescribed.

[Heat-Flow Sensor]

FIG. 16 is a conceptual diagram illustrating an example of aconfiguration of a heat-flow sensor 30 included in a heat-flowmeasurement system of the present example embodiment. The heat-flowsensor 30 has a flat plate-like appearance. FIG. 16 is a side view ofthe flat plate-like heat-flow sensor 30 as viewed from a side.

The heat-flow sensor 30 includes a substrate 31, a heat-flow detectionlayer 34, an insulating layer 35, a magnetic field application layer 36,and a cover layer 37.

The substrate 31 is a base material having an upper surface on which theheat-flow detection layer 34 is formed. The substrate 31 is made of amaterial that easily conducts heat flow. For example, the substrate 31is made of polyimide. Note that the material of the substrate 31 is notlimited to polyimide as long as heat flow is easily conducted.

The heat-flow detection layer 34 is arranged between the substrate 31and the insulating layer 35. The heat-flow detection layer 34 is aconductive magnetic body formed in a predetermined pattern having afirst end and a second end. For example, a pattern of a conductorconstituting the magnetic field application layer 36 and the pattern ofthe conductive magnetic body constituting the heat-flow detection layer34 face each other. For example, the pattern of the conductorconstituting the magnetic field application layer 36 and the pattern ofthe conductive magnetic body constituting the heat-flow detection layer34 have the same shape. For example, the magnetic field applicationlayer 36 and the heat-flow detection layer 34 are arranged such that aline of one pattern extends along a line length of the other pattern intop view.

The heat-flow detection layer 34 is favorably implemented by a softmagnetic thin film that is easily magnetized in an in-plane direction(direction in an xy plane) of the heat-flow sensor. For example, theheat-flow detection layer 34 can be implemented by a material such as aniron-aluminum alloy or a permalloy. For example, the heat-flow detectionlayer 34 favorably has a shape having a long effective length in orderto enhance sensing sensitivity. For example, the heat-flow detectionlayer 34 has a meander shape in which the first end and the second endare arranged at positions separated from each other in top view. Theshape of the heat-flow detection layer 34 is not limited to the meandershape as long as the line length of the wire from the first end to thesecond end can be made long.

The insulating layer 35 is an insulator arranged between the heat-flowdetection layer 34 and the magnetic field application layer 36. As anexample, a surface on which the magnetic field application layer 36 isarranged is referred to as a first surface, and a surface on which theheat-flow detection layer 34 is arranged is referred to as a secondsurface, of two main surfaces of the insulating layer 35. For example,the insulating layer 35 is made of polyimide. Note that the material ofthe insulating layer 35 is not limited to polyimide as long as thematerial has insulating properties.

The magnetic field application layer 36 is formed on an upper surface ofthe insulating layer 35. The magnetic field application layer 36 is aconductor formed in a predetermined pattern having a first end and asecond end. For example, the magnetic field application layer 36 isformed in the similar pattern to the heat-flow detection layer 34. Forexample, the heat-flow detection layer 34 and the magnetic fieldapplication layer 36 overlap each other in top view. For example, themagnetic field application layer 36 has a meander shape in which thefirst end and the second end are arranged at positions separated fromeach other in top view. The shape of the magnetic field applicationlayer 36 is not limited to the meander shape as long as the line lengthof the wire from the first end to the second end can be made long.

For example, the magnetic field application layer 36 is made of a metalmaterial such as copper, aluminum, or gold. Note that the material ofthe magnetic field application layer 36 is not limited to the metalmaterial such as copper, aluminum, or gold as long as the material isconductive. For example, the magnetic field application layer 36 can beformed by plating. The magnetic field application layer 36 may be formedby a method other than plating.

The cover layer 37 is formed on an upper surface of the magnetic fieldapplication layer 36. The cover layer 37 is a protective layer thatprotects the heat-flow sensor 30. The cover layer 37 is favorably madeof an insulating material having high mechanical strength, chemicalstability, heat resistance, and the like. For example, the cover layer37 is made of polyimide. Note that the material of the cover layer 37 isnot limited to polyimide as long as the material has sufficientmechanical strength, chemical stability, heat resistance, and the like.

A magnetic field is generated at a position of the heat-flow detectionlayer 34 due to current flowing through the magnetic field applicationlayer 36. The heat-flow detection layer 34 is magnetized in the in-planedirection (in-xy-plane direction) of the heat-flow sensor 30 by themagnetic field applied by the magnetic field application layer 36.

By using the equations 1 to 3 of the first example embodiment, aheat-flow value q related to a voltage value can be calculated using avoltage value V related to an electromotive force generated in theheat-flow detection layer 34.

The configuration of the heat-flow sensor 30 included in the heat-flowmeasurement system of the present example embodiment has been describedabove. Note that the configuration of FIG. 16 is an example of theconfiguration of the heat-flow sensor 30, and the configuration of theheat-flow sensor 10 included in the heat-flow measurement system of thepresent example embodiment is not limited to the configuration of FIG.16.

[Heat-Flow Measurement System]

Next, the heat-flow measurement system according to the present exampleembodiment will be described with reference to the drawings. Theheat-flow measurement system of the present example embodiment includesa direct-current power supply for causing current to flow through themagnetic field application layer 36 of the heat-flow sensor 30.

FIG. 17 is a conceptual diagram illustrating an example of aconfiguration of a heat-flow measurement system 3 of the present exampleembodiment. As illustrated in FIG. 17, the heat-flow measurement system3 includes the heat-flow sensor 30, a heat-flow measurement device 300,a direct-current power supply 310, and a voltmeter 320. In FIG. 17, theheat-flow detection layers 34 and magnetic field application layers 36,which are stacked in practice, are virtually arranged side by side.

The heat-flow sensor 30 has a structure illustrated in FIG. 16. Asillustrated in FIG. 16, the heat-flow sensor 30 includes the substrate31, the heat-flow detection layer 34, the insulating layer 35, themagnetic field application layer 36, and the cover layer 37. Inpractice, the heat-flow detection layer 34 and the magnetic fieldapplication layer 36 are stacked. In FIG. 17, the cover layer 37 isomitted.

The heat-flow detection layer 34 has a first end 341 and a second end342. The magnetic field application layer 36 has a first end 361 and asecond end 362. The heat-flow detection layer 34 and the magnetic fieldapplication layer 36 have a meander shape and overlap each other in topview.

The second end 362 of the magnetic field application layer 36 iselectrically connected to the first end 361 of the magnetic fieldapplication layer 36 across the direct-current power supply 310. Thefirst end 341 of the heat-flow sensor 30 is electrically connected tothe second end 342 of the heat-flow sensor 30. The voltmeter 320 isarranged between the first end 341 and the second end 342 of theheat-flow sensor 30.

The heat-flow measurement device 300 is connected to direct-currentpower supply 310 and voltmeter 320. The heat-flow measurement device 300drives the direct-current power supply 310 to control the currentflowing through the magnetic field application layer 36. In addition,the heat-flow measurement device 300 measures an electromotive forcegenerated in the heat-flow detection layer 34 by passage of the heatflow, using the voltmeter 320.

The direct-current power supply 310 outputs the direct current accordingto the control of the heat-flow measurement device 300. Thedirect-current power supply 310 has a positive electrode connected tothe first end 361 of the magnetic field application layer 36, and anegative electrode connected to the second end 362 of the magnetic fieldapplication layer 36. In a case where the direction of the currentflowing in the magnetic field application layer 36 is configured to beopposite, the direct-current power supply 310 has the negative electrodeconnected to the first end 361 of the magnetic field application layer36 and the positive electrode connected to the second end 362 of themagnetic field application layer 36.

The voltmeter 320 is a direct-current voltmeter connected to the firstend 341 and the second end 342 of the heat-flow detection layer 34. Thevoltmeter 320 measures a voltage between the first end 341 and thesecond end 342 of the heat-flow detection layer 34, and outputs ameasured voltage value to the heat-flow measurement device 300.

FIG. 18 is a conceptual diagram illustrating a state in which thecurrent flows through the magnetic field application layer 36 by arrows.FIG. 18 illustrates an example in which the heat-flow measurement device300 drives the direct-current power supply 310 to cause the current toflow from the first end 361 to the second end 362 of the magnetic fieldapplication layer 36.

FIG. 19 is a conceptual diagram illustrating a state in which a magneticfield generated in the magnetic field application layer 36 generates amagnetic field at the position of the heat-flow detection layer 34 whenthe current flows in the magnetic field application layer 36 asillustrated in FIG. 18. As illustrated in FIG. 19, when the currentflows through the magnetic field application layer 36, the magneticfield is generated around a wire constituting the magnetic fieldapplication layer 36 according to the Ampere's law. The magnetic fieldaround the wire constituting the magnetic field application layer 36magnetizes the heat-flow detection layer 34. As illustrated in FIG. 19,among the wires constituting the heat-flow detection layer 34, adjacentwires are magnetized in the directions opposite to each other.

FIG. 20 is a conceptual diagram illustrating a situation in which theheat flow has arrived from the outside in the state where the currentflows in the magnetic field application layer 36 as illustrated in FIGS.18 and 19. FIG. 21 is a conceptual diagram illustrating a state in whichthe electromotive force is generated in the heat-flow detection layer 34and the current flows in the heat-flow detection layer 34 in thesituation in which the heat flow has arrived from the outside in thestate where the current flows through the magnetic field applicationlayer 36.

When the heat flow passes through the heat-flow detection layer 34 fromthe substrate 31 toward the second magnetic field application layer 16as illustrated in FIG. 20, the electromotive force due to the anomalousNernst effect is generated in each conductive magnetic body constitutingthe heat-flow detection layer 34. As a result of the electromotive forcegenerated at this time being added in the heat-flow detection layer 34having the meander shape structure, an output voltage can be detectedbetween the first end 341 and the second end 342 of the heat-flowdetection layer 34. Since the output voltage between the first end 341and the second end 342 of the heat-flow detection layer 34 isproportional to the heat-flow value, the heat flow passing through theheat-flow detection layer 34 can be measured by converting the detectedoutput voltage into the heat-flow value.

In addition, the heat-flow measurement system 3 can be applied to alock-in detection method in which a magnetic field is modulated at afrequency higher than that of a noise source and a signal is evaluatedin a frequency region with less noise in order to prevent a weak signalfrom being buried in low-frequency noise and exogenous signalfluctuation such as vibration.

The configuration of the heat-flow measurement system 3 of the presentexample embodiment has been described above. The configuration of FIGS.16 to 21 is an example of the configuration of the heat-flow measurementsystem 3, and the configuration of the heat-flow measurement system 3 ofthe present example embodiment is not limited to the configuration ofFIGS. 16 to 21. Note that the heat-flow measurement system 3 of thepresent example embodiment may be configured to cause an alternatingcurrent to flow in the magnetic field application layer 36 as in thesecond example embodiment.

As described above, the heat-flow measurement system of the presentexample embodiment includes the heat-flow sensor including theinsulating layer, the magnetic field application layer, and theheat-flow detection layer. The magnetic field application layer isarranged on the first surface of the insulating layer and is made of aconductor. The heat-flow detection layer is arranged on the secondsurface facing the first surface of the insulating layer, and is made ofa conductive magnetic body. Regarding the magnetic field applicationlayer and the heat-flow detection layer, the heat-flow detection layerfaces the magnetic field application layer via the insulating layer.

In one aspect of the present example embodiment, the pattern of theconductor constituting the magnetic field application layer and thepattern of the conductive magnetic body constituting the heat-flowdetection layer face each other. In one aspect of the present exampleembodiment, the magnetic field application layer and the heat-flowdetection layer are provided via the insulating layer, and the wirepattern of the heat-flow detection layer is provided facing the wirepattern of the magnetic field application layer. In one aspect of thepresent example embodiment, the pattern of the conductor constitutingthe magnetic field application layer and the pattern of the conductivemagnetic body constituting the heat-flow detection layer have the sameshape. Further, in one aspect of the present example embodiment, theline of the pattern of the conductive magnetic body constituting theheat-flow detection layer is arranged to extend along the line length ofthe pattern of the conductor constituting the magnetic field applicationlayer in top view.

According to the present example embodiment, it is possible to provide ahighly sensitive thin-film heat-flow sensor that detects the heat flowwith a single conductive magnetic body.

The heat-flow measurement system of each of the above exampleembodiments can be used for detecting abnormal heat generation of aproduct including a heating element such as a lithium ion battery. Ingeneral temperature detection, an abnormality is detected when thetemperature of the heating element exceeds a threshold value. Incontrast, since the heat-flow measurement system of each exampleembodiment detects the heat flow from the heating element, it ispossible to detect the abnormality at the time when the heat flowexceeding the threshold value before the temperature of the heatingelement exceeds the threshold value.

In addition, since the heat-flow sensor of each example embodiment canbe thinned, even when the heat-flow sensor is attached to a surface ofan object to be measured, the heat-flow sensor is unlikely to hinder theflow of the heat flow in the perpendicular direction. Therefore, whenthe heat-flow sensor of each example embodiment is attached to a pipe ofa plant, exhaust heat from the pipe can be managed in real time. Inaddition, by taking a log of the heat flow detected by the heat-flowsensor of each example embodiment, the exhaust heat from the pipe can bemanaged by the log.

(Configuration Example)

Here, a configuration example of the heat-flow sensor according to eachexample embodiment will be described with an example. FIG. 22 is aconceptual diagram for describing an example of a structure of aheat-flow sensor 50 of the present configuration example. FIG. 22 is aside view of the flat-plate-like heat-flow sensor 50 as viewed from aside. The heat-flow sensor 50 of the present configuration examplecorresponds to the heat-flow sensor 10 of the first example embodiment.FIG. 22 illustrates a positional relationship among layers constitutingthe heat-flow sensor 50, and does not accurately illustrate the filmthickness of each layer.

The heat-flow sensor 50 includes a substrate 51, a first magnetic fieldapplication layer 52, a first insulating layer 53, a heat-flow detectionlayer 54, a second insulating layer 55, a second magnetic fieldapplication layer 56, and a cover layer 57. Since the substrate 51, thefirst magnetic field application layer 52, the first insulating layer53, the heat-flow detection layer 54, the second insulating layer 55,the second magnetic field application layer 56, and the cover layer 57are similar to the corresponding components of the heat-flow sensor 10of the first example embodiment, detailed description is omitted.

The shape of the heat-flow sensor 50 is a square having a side of 30 mmin top view. The patterns of conductors of the first magnetic fieldapplication layer 52 and the second magnetic field application layer 56are the same as the pattern of a conductive magnetic body of theheat-flow detection layer 54. In the patterns of the conductors of thefirst magnetic field application layer 52 and the second magnetic fieldapplication layer 56 and the pattern of the conductive magnetic body ofthe heat-flow detection layer 54, 149 wires are parallel, and ends ofadjacent wires are connected to form one wire, and form a meander shape.A width w₁ of the wires constituting the conductor patterns of the firstmagnetic field application layer 52 and the second magnetic fieldapplication layer 56 and the conductive magnetic body pattern of theheat-flow detection layer 54 is 100 micrometers, and an interval w₂between the wires is 100 micrometers.

The substrate 51 and the cover layer 57 are made of polyimide. Thematerial of the first magnetic field application layer 52 and the secondmagnetic field application layer 56 is copper (Cu). The heat-flowdetection layer 54 is made of Fe₃Al. The material of the heat-flowdetection layer 54 may be Ni. The first insulating layer 53 and secondinsulating layer 55 are made of polyimide.

A film thickness is of the substrate 51 and the cover layer 57 is 10micrometers. A film thickness t_(m) of the first magnetic fieldapplication layer 52 and the second magnetic field application layer 56is 10 micrometers. A film thickness to of the heat-flow detection layer54 is 1 micrometer. A film thicknesses t_(i) of the first insulatinglayer 53 and the second insulating layer 55 is 5 micrometers.

To effectively magnetize the heat-flow detection layer 54, it isdesirable to satisfy conditions of t_(m)≥t_(i) and t_(m)≥t_(d).Furthermore, to effectively magnetize the heat-flow detection layer 54,it is more desirable to satisfy the condition of t_(m)≥t_(i)+t_(d). Thefirst reason is that the thicker the first magnetic field applicationlayer 52 and the second magnetic field application layer 56 are, thesmaller the electric resistance is, and the generation of the heat flowdue to Joule heat is reduced. The second reason is that as the firstmagnetic field application layer 52 and the second magnetic fieldapplication layer 56 are thicker than the heat-flow detection layer 54,the variation in the magnetic field applied to the heat-flow detectionlayer 54 is reduced.

An example of the structure of the heat-flow sensor 50 of the presentconfiguration example has been described above. Note that theconfiguration of the heat-flow sensor 50 of FIG. 22 is an example, andthe configuration of the heat-flow sensor of each example embodiment isnot limited to the form of FIG. 22.

The heat-flow sensor according to each example embodiment has beendescribed above. Note that the heat-flow sensor of each exampleembodiment is an example, and the heat-flow sensor of each exampleembodiment is not limited to the form illustrated in the drawings.

(Hardware)

Here, a hardware configuration for implementing the heat-flowmeasurement device according to each example embodiment will bedescribed taking an information processing apparatus 90 in FIG. 23 as anexample. Note that the information processing apparatus 90 in FIG. 23 isa configuration example for executing processing of the heat-flowmeasurement device of each example embodiment, and does not limit thescope of the present invention.

As illustrated in FIG. 23, the information processing apparatus 90includes a processor 91, a main storage device 92, an auxiliary storagedevice 93, an input/output interface 95, and a communication interface96. In FIG. 23, an interface is abbreviated as an interface (I/F). Theprocessor 91, the main storage device 92, the auxiliary storage device93, the input/output interface 95, and the communication interface 96are data-communicably connected to one another via a bus 98. Inaddition, the processor 91, the main storage device 92, the auxiliarystorage device 93, and the input/output interface 95 are connected to anetwork such as the Internet or an intranet via the communicationinterface 96.

The processor 91 expands a program stored in the auxiliary storagedevice 93 or the like to the main storage device 92 and executes theexpanded program. In the present example embodiment, a software programinstalled in the information processing apparatus 90 may be used. Theprocessor 91 executes processing by the heat-flow measurement deviceaccording to the present example embodiment.

Corresponding to the heat-flow measurement device 100 (FIG. 7) of thefirst example embodiment, the functions of the power supply control unit101, the voltage measurement unit 102, and the heat-flow calculationunit 103 are implemented by an operation of the processor 91. Inaddition, corresponding to the heat-flow measurement device 200 (FIG.11) of the second example embodiment, the functions of the power supplycontrol unit 201, the voltage measurement unit 202, the heat-flowcalculation unit 203, and the correction unit 205 are implemented by theoperation of the processor 91.

The main storage device 92 has an area in which a program is expanded.The main storage device 92 may be a volatile memory such as a dynamicrandom access memory (DRAM). In addition, a nonvolatile memory such as amagnetoresistive random access memory (MRAM) may be configured and addedas the main storage device 92.

The auxiliary storage device 93 stores various data. The auxiliarystorage device 93 includes a local disk such as a hard disk or a flashmemory. Note that various data may be stored in the main storage device92, and the auxiliary storage device 93 may be omitted.

The input/output interface 95 is an interface for connecting theinformation processing apparatus 90 and a peripheral device. Thecommunication interface 96 is an interface for being connected to anexternal system or device through a network such as the Internet or anintranet on the basis of a standard or a specification. The input/outputinterface 95 and the communication interface 96 may be shared as aninterface connected to an external device.

An input device such as a keyboard, a mouse, or a touch panel may beconnected to the information processing apparatus 90 as necessary. Theseinput devices are used to input information and settings. When the touchpanel is used as the input device, a display screen of the displaydevice may also serve as the interface of the input device. Datacommunication between the processor 91 and the input device may bemediated by the input/output interface 95.

Corresponding to the heat-flow measurement device 100 (FIG. 7) of thefirst example embodiment, the function of the output unit 107 isimplemented by the operation of the input/output interface 95. Inaddition, corresponding to the heat-flow measurement device 200 (FIG.11) of the second example embodiment, the function of the output unit207 is implemented by the operation of the input/output interface 95.

Furthermore, the information processing apparatus 90 may be providedwith a display device for displaying information. In a case where thedisplay device is provided, the information processing apparatus 90favorably includes a display control device (not illustrated) forcontrolling display of the display device. The display device may beconnected to the information processing apparatus 90 via theinput/output interface 95.

Furthermore, the information processing apparatus 90 may be providedwith a drive device (not illustrated) that mediates reading and writingof data recorded on a recording medium (not illustrated). The drivedevice is connected to the bus 98, and mediates reading of data and aprogram from a recording medium, writing of a processing result of theinformation processing apparatus 90 to the recording medium, and thelike between the processor 91 and the recording medium.

The recording medium can be implemented by, for example, an opticalrecording medium such as a compact disc (CD) or a digital versatile disc(DVD). Furthermore, the recording medium may be implemented by asemiconductor recording medium such as a universal serial bus (USB)memory or a secure digital (SD) card, a magnetic recording medium suchas a flexible disk, or another recording medium. In the case where theprogram executed by the processor is recorded in the recording medium,the recording medium corresponds to a program recording medium.

The above is an example of the hardware configuration for enabling theheat-flow measurement device according to each example embodiment. Thehardware configuration of FIG. 23 is an example of a hardwareconfiguration for executing arithmetic processing of the heat-flowmeasurement device according to each example embodiment, and does notlimit the scope of the present invention. In addition, a program forcausing a computer to execute processing related to the heat-flowmeasurement device according to each example embodiment is also includedin the scope of the present invention. Further, a program recordingmedium in which the program according to each example embodiment isrecorded is also included in the scope of the present invention.

The components of the heat-flow measurement device of each exampleembodiment can be arbitrarily combined. In addition, the components ofthe heat-flow measurement device of each example embodiment may beimplemented by software or may be implemented by a circuit.

While the present invention has been described with reference to theexample embodiments, the present invention is not limited to theseexample embodiments. It will be understood by those of ordinary skill inthe art that various changes in form and details of the presentinvention may be made therein without departing from the spirit andscope of the present invention as defined by the claims.

Some or all of the above example embodiments can be described as but arenot limited to the following supplementary notes.

(Supplementary Note 1)

A heat-flow sensor including:

an insulating layer;

a magnetic field application layer arranged on a first surface of theinsulating layer and including a conductor; and

a heat-flow detection layer arranged on a second surface of theinsulating layer, the second surface facing the first surface, and theheat-flow detection layer including a conductive magnetic body, in which

the heat-flow detection layer faces the magnetic field application layervia the insulating layer.

(Supplementary Note 2)

The heat-flow sensor according to supplementary note 1, in which

a pattern of the conductor included in the magnetic field applicationlayer and a pattern of the conductive magnetic body included in theheat-flow detection layer face each other.

(Supplementary Note 3)

The heat-flow sensor according to supplementary note 2, in which

the pattern of the conductor included in the magnetic field applicationlayer and the pattern of the conductive magnetic body included in theheat-flow detection layer have a same shape.

(Supplementary Note 4)

The heat-flow sensor according to supplementary note 2 or 3, in which

a line of the pattern of the conductive magnetic body included in theheat-flow detection layer is arranged to extend along a line length ofthe pattern of the conductor included in the magnetic field applicationlayer in top view.

(Supplementary Note 5)

A heat-flow sensor including:

a substrate;

a first magnetic field application layer arranged on an upper surface ofthe substrate and including a conductor;

a first insulating layer arranged on an upper surface of the firstmagnetic field application layer;

a heat-flow detection layer arranged on an upper surface of the firstinsulating layer and including a conductive magnetic body;

a second insulating layer arranged on an upper surface of the heat-flowdetection layer; and

a second magnetic field application layer arranged on an upper surfaceof the second insulating layer and including a conductor, in which

the first magnetic field application layer, the second magnetic fieldapplication layer, and the heat-flow detection layer are configured inpatterns of a same shape overlapping in top view.

The heat-flow sensor, in which

the heat-flow detection layer faces

the first magnetic field application layer via the first insulatinglayer, and

the second magnetic field application layer via the second insulatinglayer.

(Supplementary Note 6)

The heat-flow sensor according to supplementary note 5, in which

the patterns of the conductors included in the first magnetic fieldapplication layer and the second magnetic field application layer andthe pattern of the conductive magnetic body included in the heat-flowdetection layer face each other.

(Supplementary Note 7)

The heat-flow sensor according to supplementary note 6, in which

the patterns of the conductors included in the first magnetic fieldapplication layer and the second magnetic field application layer andthe pattern of the conductive magnetic body included in the heat-flowdetection layer have a same shape.

(Supplementary Note 8)

The heat-flow sensor according to supplementary note 6 or 7, in which

a line of the pattern of the conductive magnetic body included in theheat-flow detection layer is arranged to extend along a line length ofthe pattern of the conductor included in each of the first magneticfield application layer and the second magnetic field application layerin top view.

(Supplementary Note 9)

The heat-flow sensor according to any one of supplementary notes 5 to 8,in which the heat-flow detection layer includes a soft conductivemagnetic body.

(Supplementary Note 10)

The heat-flow sensor according to any one of supplementary notes 5 to 9,in which a distance between the first magnetic field application layerand the heat-flow detection layer and a distance between the secondmagnetic field application layer and the heat-flow detection layer areequal.

(Supplementary Note 11)

The heat-flow sensor according to any one of supplementary notes 5 to10, in which the first magnetic field application layer, the secondmagnetic field application layer, and the heat-flow detection layer areconfigured in a meander pattern in which one wire is folded back.

(Supplementary Note 12)

The heat-flow sensor according to any one of supplementary notes 5 to11, in which the first magnetic field application layer and the secondmagnetic field application layer are thicker in film thickness than theheat-flow detection layer.

(Supplementary Note 13)

A heat-flow measurement system including:

the heat-flow sensor according to any one of supplementary notes 5 to12; and

a heat-flow measurement device configured to control current flowingthrough the first magnetic field application layer and the secondmagnetic field application layer, measure a voltage of the heat-flowdetection layer, and convert a measured voltage value into a heat-flowvalue.

(Supplementary Note 14)

The heat-flow measurement system according to supplementary note 13, inwhich

each of the first magnetic field application layer, the second magneticfield application layer, and the heat-flow detection layer has a firstend and a second end,

the first ends of the first magnetic field application layer and thesecond magnetic field application layer are electrically connected toeach other,

the second ends of the first magnetic field application layer and thesecond magnetic field application layer are connected via adirect-current power supply, and

the heat-flow measurement device

performs control to cause a direct current to flow from the second endof either the first magnetic field application layer or the secondmagnetic field application layer, and measures a voltage between thefirst to end and the second end of the heat-flow detection layer.

(Supplementary Note 15)

The heat-flow measurement system according to supplementary note 13, inwhich

each of the first magnetic field application layer, the second magneticfield application layer, and the heat-flow detection layer has a firstend and a second end,

the first ends of the first magnetic field application layer and thesecond magnetic field application layer are electrically connected toeach other,

the second ends of the first magnetic field application layer and thesecond magnetic field application layer are connected via analternating-current power supply, and

the heat-flow measurement device

performs control to cause an alternating current to flow from the secondend of each of the first magnetic field application layer and the secondmagnetic field application layer, and measures a voltage between thefirst end and the second end of the heat-flow detection layer.

(Supplementary Note 16)

The heat-flow measurement system according to supplementary note 15, inwhich

the heat-flow measurement device corrects the heat-flow value with anaverage value of a maximum value and a minimum value of the voltagebetween the first end and the second end of the heat-flow detectionlayer as a baseline.

REFERENCE SIGNS LIST

-   1, 2, 3 heat-flow measurement system-   10, 20, 30 heat-flow sensor-   11, 21, 31 substrate-   12, 22 first magnetic field application layer-   13, 23 first insulating layer-   14, 24, 34 heat-flow detection layer-   15, 25 second insulating layer-   16, 26 second magnetic field application layer-   17, 37 cover layer-   35 insulating layer-   36 magnetic field application layer-   100, 200, 300 heat-flow measurement device-   101, 201 power supply control unit-   102, 202 voltage measurement unit-   103, 203 heat-flow calculation unit-   107, 207 output unit-   110, 310 direct-current power supply-   120, 220, 320 voltmeter-   130, 230 output device-   205 correction unit-   210 alternating-current power supply

What is claimed is:
 1. A heat-flow sensor comprising: an insulatinglayer; a magnetic field application layer arranged on a first surface ofthe insulating layer and composed of a conductor; and a heat-flowdetection layer arranged on a second surface of the insulating layer,the second surface facing the first surface, and the heat-flow detectionlayer composed of a conductive magnetic body, wherein the heat-flowdetection layer faces the magnetic field application layer via theinsulating layer.
 2. The heat-flow sensor according to claim 1, whereina pattern of the conductor comprising the magnetic field applicationlayer and a pattern of the conductive magnetic body comprising theheat-flow detection layer face each other.
 3. The heat-flow sensoraccording to claim 2, wherein the pattern of the conductor comprisingthe magnetic field application layer and the pattern of the conductivemagnetic body comprising the heat-flow detection layer have a sameshape.
 4. The heat-flow sensor according to claim 2, wherein a line ofthe pattern of the conductive magnetic body comprising the heat-flowdetection layer is arranged to extend along a line length of the patternof the conductor comprising the magnetic field application layer in topview.
 5. A heat-flow sensor comprising: a substrate; a first magneticfield application layer arranged on an upper surface of the substrateand composed of a conductor; a first insulating layer arranged on anupper surface of the first magnetic field application layer; a heat-flowdetection layer arranged on an upper surface of the first insulatinglayer and composed of a conductive magnetic body; a second insulatinglayer arranged on an upper surface of the heat-flow detection layer; anda second magnetic field application layer arranged on an upper surfaceof the second insulating layer and composed of a conductor, wherein thefirst magnetic field application layer, the second magnetic fieldapplication layer, and the heat-flow detection layer are configured inpatterns of a same shape overlapping in top view.
 6. The heat-flowsensor according to claim 5, wherein the patterns of the conductorscomprising the first magnetic field application layer and the secondmagnetic field application layer and the pattern of the conductivemagnetic body comprising the heat-flow detection layer face each other.7. The heat-flow sensor according to claim 6, wherein the patterns ofthe conductors comprising the first magnetic field application layer andthe second magnetic field application layer and the pattern of theconductive magnetic body comprising the heat-flow detection layer have asame shape.
 8. The heat-flow sensor according to claim 6, wherein a lineof the pattern of the conductive magnetic body comprising the heat-flowdetection layer is arranged to extend along a line length of the patternof the conductor included in each of the first magnetic fieldapplication layer and the second magnetic field application layer in topview.
 9. The heat-flow sensor according to claim 5, wherein theheat-flow detection layer is composed of a soft conductive magneticbody.
 10. The heat-flow sensor according to claim 5, wherein a distancebetween the first magnetic field application layer and the heat-flowdetection layer and a distance between the second magnetic fieldapplication layer and the heat-flow detection layer are equal.
 11. Theheat-flow sensor according to claim 5, wherein the first magnetic fieldapplication layer, the second magnetic field application layer, and theheat-flow detection layer are configured in a meander pattern in whichone wire is folded back.
 12. The heat-flow sensor according to claim 5,wherein the first magnetic field application layer and the secondmagnetic field application layer are thicker in film thickness than theheat-flow detection layer.
 13. A heat-flow measurement systemcomprising: the heat-flow sensor according to claim 5; and a heat-flowmeasurement device configured to control a current flowing through thefirst magnetic field application layer and the second magnetic fieldapplication layer, measure a voltage of the heat-flow detection layer,and convert a measured voltage value into a heat-flow value.
 14. Theheat-flow measurement system according to claim 13, wherein each of thefirst magnetic field application layer, the second magnetic fieldapplication layer, and the heat-flow detection layer has a first end anda second end, the first ends of the first magnetic field applicationlayer and the second magnetic field application layer are electricallyconnected to each other, the second ends of the first magnetic fieldapplication layer and the second magnetic field application layer areconnected via a direct-current power supply, and the heat-flowmeasurement device is configured to perform control to cause a directcurrent to flow from the second end of either the first magnetic fieldapplication layer or the second magnetic field application layer, andmeasure a voltage between the first end and the second end of theheat-flow detection layer.
 15. The heat-flow measurement systemaccording to claim 13, wherein each of the first magnetic fieldapplication layer, the second magnetic field application layer, and theheat-flow detection layer has a first end and a second end, the firstends of the first magnetic field application layer and the secondmagnetic field application layer are electrically connected to eachother, the second ends of the first magnetic field application layer andthe second magnetic field application layer are connected via analternating-current power supply, and the heat-flow measurement deviceis configured to perform control to cause an alternating current to flowfrom the second end of each of the first magnetic field applicationlayer and the second magnetic field application layer, and measure avoltage between the first end and the second end of the heat-flowdetection layer.
 16. The heat-flow measurement system according to claim15, wherein the heat-flow measurement device is configured to correctthe heat-flow value with an average value of a maximum value and aminimum value of the voltage between the first end and the second end ofthe heat-flow detection layer as a baseline.